The present invention generally relates to a film wrapping machine for wrapping articles with heat-shrinkage synthetic films, and in particular to an adjustable film feeding device capable to accommodate films of different size for wrapping articles of different sizes.
Heat shrinkage films are widely used to package articles or consumer products, such as CDs (Compact Disks). The packaging is done by placing a tubular film over the article to be packaged. One way to fit the tubular film over the article is to first place the tubular film over a film feeding cylinder with the article positioned below the film feeding cylinder. Rollers are then positioned in physical contact with the film feeding cylinder for frictionally driving the tubular film downward and fitting over the article.
A complicated transmission/driving mechanism is required to control the operation of the rollers for manipulation of the moving speed of the tubular film toward the article. Such a complicated mechanism makes it difficult to change the spatial relationship of the rollers with respect to the film feeding cylinder. Thus re-arrangement of the rollers with respect to the film feeding cylinder for accommodating films of different sizes for packaging different articles cannot be done without replacing the original transmission/driving mechanism with one of different specification or without re-designing the transmission/driving mechanism. Cost can thus be increased and shutdown time of the packaging machine may be undesirably extended in changing or rearranging the transmission/driving mechanism.
It is thus desirable to provide an adjustable wrappage film feeding device for alleviating the above-discussed problems.
Accordingly, an object of the present invention is to provide an adjustable wrappage film feeding device comprising location-adjustable film feeding rollers for accommodating films of different sizes.
Another object of the present invention is to provide an adjustable wrappage film feeding device wherein adjustment for accommodating films of different sizes can be done with simple and efficient operations thereby reducing shutdown time.
A further object of the present invention is to provide an adjustable wrappage film feeding device which allows films of different sizes without replacement of transmission mechanism.
Yet a further object of the present invention is to provide an adjustable wrappage film feeding device which allows films of different sizes without re-designing transmission mechanism.
In accordance with the present invention, an adjustable wrappage film feeding device comprises a chassis having end plates rotatably supporting a driving shaft therebetween. The driving shaft is driven by a motor via a wormxe2x80x94worm gear transmission. Two first bevel gears are mounted on the driving shaft to be rotatable in unison with the driving shaft while being allowed to axially move with respect to the driving shaft. A screw rod is rotatably supported by the end plates and threadingly engages two movable carriages that are spaced from each other a distance. By rotating the screw rod, the carriages are driven toward/away from each other and thus changing the distance therebetween. Each carriage rotatably carries a roller adapted to drivingly engage and convey a film in a predetermined direction toward an article to be packaged. Each roller is coupled to a corresponding one of the first bevel gears by a second bevel gear that mates the corresponding first bevel gear. The change of distance between the carriages allows accommodation of film of different sizes. The axial movability of the first bevel gears with respect to the driving shaft maintains mating engagement between the first and second bevel gears when the carriages are moved by the screw rod.